DE112018001936T5 - Lubrication system for a transmission arranged in a vehicle - Google Patents

Abstract

The present invention relates to a lubrication system (8) for a transmission (3), which is arranged in a motor vehicle (1). The lubrication system has a first lubrication circuit (9) with a mechanical pump (12) which supplies lubricant to the transmission (3) and a second lubrication circuit (20) with an electric pump which supplies lubricant to the transmission (3). The mechanical pump (12) is driven by a component in a drive train of the vehicle via a mechanical power transmission (13). The mechanical power transmission (13) comprises a coupling component (15) which is movably arranged between a connected state in which it transmits a driving force from the component (14) to the mechanical pump (12) and a separate state in which it is the Transmission of driving force from the component (14) to the mechanical pump (12) interrupts. A control unit (26) is arranged to move the coupling component (15) into the disconnected state when the electric pump (21) has an ability to deliver a required lubricant flow to the transmission (3).

Description

BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates to a lubrication system for a transmission arranged in a vehicle according to the preamble of patent claim 1.

A drive train of a hybrid vehicle may include an internal combustion engine, an electric machine, and a transmission. Typically, a mechanical pump lubrication system is used to deliver lubricant in the form of an oil to the transmission. The mechanical pump can be a positive displacement pump that delivers a constant volume in each pump cycle. The pump can be driven by a component in the drive train, such as the intermediate shaft of the transmission. In this case the mechanical pump circulates an oil flow in the lubrication system which is related to the speed of the intermediate shaft. In particular in operating conditions in which the mechanical pump operates at a high speed and the required drive torque of the vehicle is low, the mechanical pump delivers an excessive flow of lubricant to the transmission. During such an operating state, the mechanical pump consumes an unnecessary amount of energy.

The electric machine can drive the hybrid vehicle alone or together with the internal combustion engine. In other operating states, the electric machine functions as a generator that supplies electrical energy to an energy store. In any case, the machine gets hot during operation. Conventional cooling of an electrical machine can be achieved by air or water which is conducted past an outer surface of a housing enclosing the electrical machine. A more effective cooling method is to spray oil on the stator windings of the electrical machine. An electric pump can be arranged in a cooling circuit that supplies oil to the electric machine.

US 2016/0123457 shows a two-circuit lubrication method for lubricating a main power transmission gear of an aircraft. Each circuit contains a pump that is used to draw in lubricant via suction points that are arranged at different depths in a lubricant tank. The flows in the circles can be started and stopped individually to prevent the lubricant in the tank from draining.

SUMMARY OF THE INVENTION

The object of the invention is to provide a lubrication system which provides lubrication of a transmission arranged in a vehicle in a reliable and energy-efficient manner.

This object is achieved by the lubrication system, which is specified in the characterizing part of patent claim 1. The lubrication system comprises a first circuit with a mechanical pump, by means of which it is possible to direct lubricants to the gearbox. A mechanical pump provides the gearbox with a lubricant flow depending on its speed. However, the speed of the mechanical pump is not always related to the lubricant flow required by the gearbox. In particular in operating states in which the drive torque of the vehicle is low, a mechanical pump conveys an excessive flow of lubricant to the transmission. During such operating conditions, the mechanical pump consumes an unnecessary amount of energy. The lubrication system includes a second cooling circuit with an electric pump that is driven by an electric motor. An electric pump is easy to control within a wide speed range, so that it delivers a lubricant flow to the gearbox with high accuracy. Given this, it is more energy efficient to use the electric pump instead of the mechanical pump in most operating conditions. The presence of the coupling component in the mechanical power transmission, which transmits a driving force from a component in the drive train of the transmission to the mechanical pump, makes it possible to interrupt the operation of the mechanical pump in a simple manner. This option can be used, for example, under operating conditions during which the mechanical pump delivers an excessive flow of lubricant to the transmission. During such an operating condition, it is possible to use the electric pump and to supply a lubricant flow to the transmission which corresponds to the required lubricant flow with a high degree of accuracy. The design of the lubrication system makes it possible to use the pump that is best suited to deliver lubricant to the transmission in the current operating condition.

According to one embodiment of the present invention, the lubrication system comprises a control unit which is set up to control the coupling component, to control the operation of the electric pump, to receive information about at least one operating parameter and to control the operation of the pumps in the light of this information. The control unit can have access to stored Have data indicating which of the pumps should be used during different operating conditions.

According to one embodiment of the present invention, the control unit is set up to receive information about an operating parameter relating to the viscosity of the lubricant in the lubricant store and to initiate operation of the mechanical pump and no operation of the electric pump under operating conditions in which the viscosity of the lubricant is higher as a certain value. The operating parameter can be the temperature of the lubricant. The viscosity of a lubricant such as an oil is significantly higher at low temperatures than at high temperatures. A mechanical pump that is driven by a component in the drive train of the transmission has the ability to pump oil with a very high viscosity. An electric pump that is not oversized does not have this ability.

According to one embodiment of the present invention, the control unit can be configured to estimate whether the electric pump has the ability to supply the required lubricant flow to the transmission during operating conditions in which the viscosity of the lubricant in the lubricant reservoir is lower than the determined value. Given that it is possible to deliver a required flow of lubricant to the gearbox with greater accuracy than the mechanical pump during almost all operating conditions, it is desirable to use the electric pump as much as possible if that Lubricant has reached a normal operating temperature. The control unit may be configured to receive information about the drive torque of the vehicle and to estimate whether the electrical pump has the ability to deliver the required lubricant flow to the transmission based on this information. The required flow of lubricant to the transmission depends on the drive torque of the vehicle. The control unit can have access to data or can be able to calculate the required lubricant flow to the transmission on the basis of information about the current drive torque of the vehicle. If the drive torque is low, the electric pump is likely to be able to deliver the required flow of lubricant to the transmission.

According to one embodiment of the present invention, the control unit can be configured to move the coupling component into the disconnected state when it is estimated that the electric pump is able to deliver the required lubricant flow to the transmission, and thus the electric pump control that it delivers the required lubricant flow to the gearbox. On the other hand, the control unit can be configured to move the coupling component into the connected state if it is estimated that the electric pump is unable to supply the required flow of lubricant to the transmission and to control the operation of the electric pump that the electric pump and the mechanical pump together deliver the required lubricant flow to the gearbox. In the latter case, the control unit can estimate the lubricant flow provided by the mechanical pump by means of information about its speed and control the operation of the electric pump in such a way that it provides the difference between the required lubricant flow and the lubricant flow supplied by the mechanical pump.

According to one embodiment of the present invention, the second lubrication circuit further comprises an extension between the lubricant source and another object to be lubricated or cooled during operation of the vehicle. In this case, the second lubrication circuit and the electric pump have two functions, namely to lubricate the transmission and to cool and / or lubricate the other object. The other object can be an electrical machine. In this case, the vehicle can be a hybrid vehicle driven by the electric machine and an internal combustion engine. The cooling requirement of the electrical machine can change quickly and it can be high during certain operating conditions. In view of these circumstances, it is appropriate to use an electric pump to supply lubricant to the electric machine because it is easy to control it with high accuracy over a wide speed range. In addition, an electric pump is a good addition to a mechanical pump as it has different properties.

According to one embodiment of the present invention, the second lubrication circuit contains a valve arrangement, by means of which it is possible to direct the lubricant flow to the transmission and / or to the further object. The valve members can be two-way valves which are movably arranged between an open position and a closed position. The control unit can set one of the valve members into the open position and the other valve member into the closed position if the lubricant flow in the second lubrication circuit is to be delivered to the transmission or the further object. If both valve elements are in the open position, part of the lubricant flow in the second lubrication circuit is delivered to the gearbox and on remaining part of the current in the second lubrication circuit is delivered to the further object.

According to an embodiment of the present invention, the first lubrication circuit and the second lubrication circuit receive lubricant from a common lubricant source. The use of a common lubricant that is pumped from a common lubricant source enables the lubrication system to be designed to be compact and contain fewer components than two separate lubrication systems. Because a common lubricant is used in the two lubrication circuits, it may be sufficient to arrange a lubricant filter in one of the two lubrication circuits.

According to one embodiment of the present invention, the first lubrication circuit and the second lubrication circuit comprise a common starting part in which lubricant is sucked out of the lubricant sump. The initial part can comprise a common suction strainer. In addition, such a common initial part reduces the total pipe length of the first lubrication circuit and the second lubrication circuit. Of course, it is possible to use two separate starting parts in the lubrication systems. The first lubrication circuit can comprise a section which contains the mechanical pump and a first check valve, the second lubrication circuit can comprise a section which contains the electric pump and a second check valve, and said sections of the first lubrication circuit and the second lubrication circuit are connected in parallel , The task of the check valves is to prevent a lubricant flow in the wrong direction during an operating condition during which the corresponding pumps are not in operation. The first lubrication circuit and the second lubrication circuit may include a common end portion that supplies lubricant to the transmission. Such a common end part further reduces the total pipe length of the first lubrication circuit and the second lubrication circuit.

The present invention also relates to a vehicle which comprises a lubrication system according to claims 1 to 14.

list of figures

• 1 ein Fahrzeug mit einem Schmiersystem gemäß der Erfindung zeigt, und
• 2a bis c das Schmiersystem bei drei unterschiedlichen Betriebsbedingungen genauer zeigt.

A preferred embodiment of the invention is described below by way of example with reference to the accompanying figures, in which:

• 1 shows a vehicle with a lubrication system according to the invention, and
• 2a to c shows the lubrication system in more detail under three different operating conditions.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

1 shows a drive train of a hybrid vehicle 1 , The drive train includes an internal combustion engine 2 , a gear 3 , a number of drive shafts 4 and drive wheels 5 , An electrical machine 6 is in a housing between the internal combustion engine 2 and the transmission 3 arranged. The electrical machine delivers under certain operating conditions 6 Power to the drivetrain. In other operating conditions, the electrical machine works as a generator, during which it sends electrical energy to an energy storage device, not shown, of the vehicle 1 supplies. The internal combustion engine 2 can the vehicle alone or together with the electrical machine 6 drive. The gear 3 transmits power from the internal combustion engine 2 and the electrical machine 6 on the drive shafts 4 and the drive wheels 5 , The gear 3 has components 7 in the form of bearings, shafts and gears that need to be lubricated and cooled while the vehicle is operating. The electrical machine 6 is heated up during operation and must be cooled. In 1 is schematically a lubrication system 8th reproduced that the components 7 in the transmission 3 and the electrical machine 6 lubricates and cools.

2a to 2c show the lubrication system 8th more accurate. The lubrication system 8th includes a first lubrication circuit 9 with an extension of an oil sump 10 to the gearbox 3 , An entrance part 9a of the first lubrication circuit 9 has a suction strainer 11 on. An intermediate part 9b of the first lubrication circuit 9 contains a mechanical pump 12 , The mechanical pump 12 can be a positive displacement pump with a fixed displacement. Thus the mechanical pump delivers 12 constant oil volume through the lubrication circuit during each pump cycle and at a given speed 9 , The mechanical pump 12 is by means of a mechanical power transmission 13 from a component in the drive train of the vehicle 1 driven. In the present case, the component is an intermediate shaft 14 in the transmission 3 , The mechanical pump 12 pumps an oil flow into the lubrication circuit 9 which is related to the speed of the intermediate shaft 14 changes. During different operating conditions of the vehicle 1 can be from the mechanical pump 12 in the lubrication circuit 9 change pumped oil flow within a relatively large range. The mechanical power transmission 13 comprises a coupling component 15 with which it is possible the intermediate shaft 14 from the mechanical pump 12 to separate. The intermediate part also includes 9a an oil filter in the first lubrication circuit 16 located at a point downstream of the mechanical pump 12 is arranged. A bypass valve 17 is in a bypass line 18 of the oil filter 16 arranged. Only if the oil filter 16 the bypass valve should be blocked 17 be open. A check valve 19 is at a location downstream of the oil filter 16 arranged. The task of the check valve 19 is to allow oil flow in one direction, but to prevent oil flow in the opposite direction. Finally, the first lubrication circuit includes 9 an end part 9c , the oil to the transmission 3 passes.

The lubrication system 8th includes a second lubrication circuit 20 with an extension from the oil sump 10 to the gearbox 3 , The second lubrication circuit 20 has an initial part 20a that with the opening part 9a of the first lubrication circuit 9 matches. Accordingly, have the first lubrication system 9 and the second lubrication system 20 a common suction strainer 11 , The second lubrication circuit 20 has an intermediate part 20b with an electric pump 21 , The electric pump 21 is powered by an electric motor 22 driven. That through the second lubrication circuit 20 pumped oil flow changes with the speed of the electric pump 21 , The intermediate part 20b of the second lubrication circuit 20 also has a valve member 23 on. The valve member 23 is adjustable to an open position in which there is an oil flow to the gearbox 3 allowed, and in a closed position in which there is an oil flow to the transmission 3 in derogation. The intermediate part also includes 20b a check valve in the second lubrication circuit 24 , which allows oil flow in one direction, but prevents oil flow in the opposite direction. The second lubrication circuit 20 has one with the end part 9c of the first lubrication circuit 9 matching end part 20c , the oil to the transmission 3 passes. The second lubrication circuit 20 includes a fourth part 20d with which it is possible to add oil to the electrical machine 6 to lead. The fourth part 20d of the second lubrication circuit 20 has an inlet at a point between the electric pump 21 and the valve member 23 in the intermediate part 20b of the second lubrication circuit 20 is arranged. The fourth part 20d of the second lubrication circuit 20 contains a valve member 25 , The valve member 25 is adjustable to an open position in which there is an oil flow through the fourth part 20d to the electrical machine 6 allowed, and in a closed position in which there is an oil flow to the electrical machine 6 in derogation.

The lubrication system includes a control unit 26 , which receives information about a number of operating parameters. In the present case, the control unit receives 26 information 27a about the temperature of the oil in the oil sump 10 , Information 27b about the temperature of the electrical machine 26 , Information 27c about the required drive torque of the vehicle and information 27d about the speed of the intermediate shaft 14 in the transmission 3 , Given this information 27a to d controls the control unit 26 the operation of the mechanical pump 12 , the electric pump 21 and the position of the valve members 23 . 25 , The control unit 26 controls the mechanical pump 12 by means of the coupling component 15 , The control unit 26 guides a movement of the coupling component 15 in a connected state and a separated state by means of an actuator 28 on. The control unit 26 controls the electric pump 21 by means of the electric motor 22 , The valve members 23 . 25 can be solenoid valves.

During an initial operating period after a cold start of the vehicle 1 has the oil in the oil sump 10 a low temperature and high viscosity. During such an operating state, it requires a relatively high pumpability to extract oil from the oil sump 10 to the gearbox 3 to pump. Only the mechanical pump 12 has such a high pumpability. As a result, the control unit moves 26 if they have information 27a receives, which indicates that the oil has a lower temperature than a certain temperature, the coupling component 15 by means of the actuator 28 in the connected state, so the mechanical pump 12 through the intermediate shaft 14 of the transmission 3 is driven. As a result, the mechanical pump pumps 12 Oil from the oil sump 10 through the first lubrication circuit 9 to the gearbox 3 , During an initial operating period after a cold start of the vehicle 1 there is no need to cool the electrical machine 6 ,

The control unit receives after a certain operating time 26 information 27a , which indicates that the temperature of the oil has risen to a temperature higher than the certain temperature. The viscosity of the oil has now decreased to a level at which it is the electric pump 21 is possible oil from the oil sump 10 to pump. Since it is not possible by the mechanical pump 12 Controlling the pumped oil flow with high accuracy are the losses of the mechanical pump 12 higher than the losses of the electric pump 21 , Especially in operating conditions where the intermediate shaft 14 is driven at a high speed and at the same time the drive torque of the vehicle 1 is low, the mechanical pump pumps 12 usually too high an oil flow to the gearbox 3 , In order to reduce the aforementioned pumping losses, the control unit is 26 set up the electric pump 21 to use as much as possible and the mechanical pump 12 only during start-up, when the oil has a high viscosity, and in operating conditions during which the electric pump 21 is unable to deliver a required oil flow to the transmission 3 and to the electrical machine 6 to deliver.

2a shows an operating condition in which the control unit 26 information 27a which indicates that the oil in the oil sump 10 has a higher temperature than the certain temperature, and information 27b , which indicates that the electrical machine 6 has a higher temperature than a threshold temperature at which the electrical machine 6 must be cooled. Consequently, it is possible to use the electric pump 21 to be used, however, it must mainly be used for the electrical machine 6 to cool. The control unit also receives 26 information 27c about the speed of the intermediate shaft 14 and thus the oil flow capability of the mechanical pump 12 , Finally the control unit receives 26 information 27d about the drive torque of the vehicle 1 and thus the required oil flow to the gearbox 3 , Given this information, the control unit estimates 26 during this operating state that the mechanical pump 12 is able to deliver the required oil flow to the gearbox 3 to deliver and that the electric pump 21 is unable to deliver the required oil flow to the transmission 3 in addition to the oil flow for the electrical machine 6 to deliver. Consequently, the control unit 26 the valve member 23 in a closed position and the valve member 25 in an open position. Then the control unit activates 26 the electric pump 21 so that they have the required oil flow to the electrical machine 6 supplies. The control unit also activates 26 the actuator 28 so that it is the coupling component 15 moved to the connected state if it is not already in this state. This measure means that the mechanical pump 12 an oil flow to the transmission 3 starts to pump, which corresponds at least to the required oil flow.

2 B shows an operating state in which the control unit 26 information 27a which indicates that the oil in the oil sump 10 has a higher temperature than the certain temperature, and information 27b , which indicates that the electrical machine 6 has a higher temperature than a threshold temperature at which the electrical machine 6 must be cooled. Consequently, it is possible to use the electric pump 21 to be used, however, it must mainly be used for the electrical machine 6 to cool. The control unit also receives 26 information 27c about the speed of the intermediate shaft 14 and thus the oil flow capability of the mechanical pump. The control unit also receives 26 information 27d about the drive torque of the vehicle 1 and thus the required oil flow to the gearbox 3 , Given this information, the control unit estimates 26 during this operating state that the mechanical pump 12 is unable to deliver the required oil flow to the transmission 3 to deliver that however the mechanical pump 12 and the electric pump 21 together are able to deliver the required oil flow to the gearbox 3 to deliver. Consequently, the control unit 26 the valve member 23 in an open position and the valve member 25 in an open position. Then the control unit activates 26 the electric pump 21 so that they get the required oil flow to the gearbox 3 and to the electrical machine 6 supplies. The control unit also activates 26 the actuator 28 so that it is the coupling component 15 moved to the connected state if it is not already in this position. This measure means that the mechanical pump 12 an oil flow to the transmission 3 starts pumping together with the oil flow from the electric pump 21 the required oil flow to the gearbox 3 equivalent.

2c shows an operating state in which the control unit 26 information 27a which indicates that the oil in the oil sump 10 has a higher temperature than the certain temperature, and information 27b , which indicates that the electrical machine 6 has a lower temperature than a threshold temperature at which the electrical machine 6 must be cooled. It is thus possible to use the electric pump 21 to use, and it need not be used for the electric machine 6 to cool. The control unit also receives 26 information 27c about the speed of the intermediate shaft 14 and thus the oil flow capability of the mechanical pump. The control unit also receives 26 information 27d about the drive torque of the vehicle 1 and thus the required oil flow to the gearbox 3 , Given this information, the control unit estimates 26 during this operating state that the electric pump 21 is able to deliver the required oil flow to the gearbox 3 to deliver. Consequently, the control unit 26 the valve member 23 in an open position and the valve member 25 in a closed position. Then the control unit activates 26 the electric pump 21 so that they get the required oil flow to the gearbox 3 supplies. It also activates the control unit 26 the actuator 28 so that it is the coupling component 15 moved to the disconnected state. This measure causes the driving force to be transferred to the mechanical pump via the mechanical power transmission 12 ceases.

During the in 2 and 3 shown operating conditions, the oil flow to the gearbox 3 at least partially from the electric pump 21 delivered. During these operating conditions it is possible to use the electric pump 21 to control the oil flow to the transmission 3 corresponds to the required oil flow with high accuracy. During these operating conditions it is possible to switch one large oil flow to the transmission 3 to avoid and avoid unnecessary energy losses.

The invention is in no way limited to the embodiment to which the drawing refers, but can be varied freely within the scope of the claims. For example, the lubrication system can be used to deliver lubricants to only one transmission. Furthermore, the motor vehicle need not be a hybrid vehicle, it may be a vehicle that is driven by a single engine, such as an electric machine or an internal combustion engine.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2016/0123457 [0004]

Claims (15)

Lubrication system (8) for a transmission (3) arranged in a motor vehicle (1), with a first lubrication circuit (9), which has an extension between a lubricant source (10) and the transmission (3), a mechanical pump (12), which is set up to supply a lubricant flow from the lubricant source (10) through the first lubrication circuit (9) to the transmission (3), and a mechanical power transmission (13) which is set up to transmit a driving force from a component (14) to be transmitted in a drive train of the vehicle (1) to the mechanical pump (12), characterized in that the lubrication system has a second lubrication circuit (20) which is an extension between a lubricant source (10) and the gearbox (3), an electric pump (21), which is configured to supply a lubricant flow in the second lubrication circuit (20) from the lubricant source (10) to the transmission (3), and a coupling component (15) of the mechanical force Transmission (13), which is movably arranged between a connected state in which it transmits a driving force from the component (14) to the mechanical pump (12), and a separate state in which it transmits the driving force from the component ( 14) to the mechanical pump (12). Lubrication system after Claim 1 , characterized in that the lubrication system comprises a control unit (26) which is set up to control the activation of the mechanical pump (12) by means of the coupling component (15), the operation of the electric pump (21) by means of an electric motor (22) to control, receive information (27a-d) on at least one operating parameter and control the operation of the mechanical (12) and the electric pump (21) in the light of this information (17a-27d). Lubrication system after Claim 2 , characterized in that the control unit (26) is set up to receive information (27a) about an operating parameter relating to the viscosity of the lubricant in the lubricant store (10) and to operate the mechanical pump (12) and not to operate the electric pump ( 21) to be initiated in operating conditions in which the viscosity of the lubricant is higher than a certain value. Lubrication system after Claim 3 , characterized in that the control unit (26) is configured to estimate whether the electric pump (21) has an ability to deliver the required lubricant flow to the transmission (3) during operating conditions in which the viscosity of the lubricant is lower than the determined value , Lubrication system after Claim 4 , characterized in that the control unit (26) is set up to receive information (27d) about the drive torque of the vehicle and to estimate whether, in the light of this information (27d), the electric pump (21) has an ability to deliver the required lubricant flow for Gearbox (3) has. Lubrication system after Claim 4 or 5 , characterized in that the control unit (26) is set up to initiate a movement of the coupling component (15) into the disconnected state if the electric pump (21) is assumed to be able to deliver the required lubricant flow to the To deliver gear (3), and to control the electric pump (21) so that it supplies the required flow of lubricant to the gear (3). Lubrication system after Claim 4 or 5 , characterized in that the control unit (26) is set up to initiate movement of the coupling component (15) into the connected state if the electric pump (21) is assumed to be unable to supply the required lubricant flow to deliver to the transmission (3), and to control the operation of the electric pump (21) so that it alone or together with the mechanical pump (12) delivers the required oil flow to the transmission (3). Lubrication system according to one of the preceding claims, characterized in that the second lubrication circuit comprises an extension between the lubricant source (10) and a further object (6) to be lubricated or cooled during operation of the vehicle (1). Lubrication system after Claim 8 , characterized in that the further object is an electrical machine (6). Lubrication system after Claim 8 or 9 , characterized in that the second lubrication circuit (20) has a valve arrangement (23, 25) by means of which it is possible to direct the lubricant flow to the transmission (3) and / or to the further object (6). Lubrication system according to one of the preceding claims, characterized in that the first lubrication circuit (9) and the second lubrication circuit (20) receive lubricant from a common lubricant source (10). Lubrication system according to one of the preceding claims, characterized in that the first lubrication circuit (9) and the second lubrication circuit (20) have a common starting part (9a, 20a) have, in which lubricant is sucked out of the lubricant sump (10). Lubrication system according to one of the preceding claims, characterized in that the first lubrication circuit (9) has a part (9b) with the mechanical pump (12) and a first check valve (19), that the second lubrication circuit (20) has a part (20b) with the electric pump (21) and a second check valve (24), and that the parts (9b, 20b) of the first lubrication circuit and the second lubrication circuit (20) are connected in parallel. Lubrication system according to one of the preceding claims, characterized in that the first lubrication circuit (9) and the second lubrication circuit (20) have a common end part (9a, 20a) which supplies lubricant to the transmission (3). Vehicle with a lubrication system according to one of the preceding Claims 1 to 14 ,

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